DC distribution network fault detection method and related devices based on high-frequency voltage at the magnetic ring boundary line side

Abstract

This invention provides a method and related apparatus for fault detection in DC distribution networks based on high-frequency voltage at the magnetic ring boundary line side. The method includes a fault initiation criterion responding to the DC distribution network system under test. If a disturbance occurs in the system, the polarity of the transient power after the fault is used to determine whether the fault direction is a positive fault. If not, it is determined to be a reverse fault. If so, a modulo-1 voltage fault component is calculated based on the positive and negative voltages at the magnetic ring line side. The time-frequency distribution matrix of this component is calculated using a Stockwell transform. A synchronous squeezing transform is performed on this matrix to obtain the time-frequency distribution after energy redistribution. The sum of the moduli of the modulo-1 high-frequency voltage fault components is calculated, and the fault is determined to be inside or outside the fault zone. If the sum of the moduli is not less than a set value, it is determined to be an inside-zone fault; otherwise, it is determined to be a positive outside-zone fault. This invention proposes a fault identification criterion based on magnetic ring boundary elements and synchronous squeezing Stockwell transform, which can effectively reduce costs.

Description

Technical Field

[0001] This invention belongs to the field of fault detection technology for DC distribution networks, specifically relating to a fault detection method and related device for DC distribution networks based on high-frequency voltage at the boundary line side of a magnetic ring. Background Technology

[0002] As new power systems continue to develop towards higher efficiency, intelligence, and low carbon emissions, DC distribution networks, as a key carrier connecting renewable energy, energy storage systems, and DC loads, have become one of the core architectures for building the future energy internet. Compared to traditional AC distribution networks, DC distribution networks offer significant advantages in reducing line losses and flexibly adjusting power, playing a crucial role in promoting the consumption of intermittent renewable energy sources such as photovoltaics and wind power, and adapting to the clustered development of DC loads such as data centers and electric vehicle charging facilities.

[0003] Power lines are the components with the highest failure probability in power systems. Line protection methods mainly include dual / multi-terminal quantity protection and single-terminal quantity protection. Dual / multi-terminal quantity protection utilizes dual- or multi-terminal information for fault location identification, such as directional longitudinal protection and current differential protection. However, in large-scale applications of DC distribution networks, the large number of distribution lines, flexible and varied topologies, and complex communication channel configurations result in high costs. Single-terminal quantity protection uses only local information for fault identification, making it a more cost-effective solution, especially for boundary protection. By coordinating protection on one side of the line with boundary elements on the other side, it is expected to be possible to identify faults across the entire line using single-terminal electrical quantities. Currently, there are proposed methods for flexible DC distribution network fault protection, such as the improved current-limiting reactor voltage based on empirical wavelet transform.

[0004] Existing technologies propose low-voltage DC distribution network protection methods based on power electronic transformer fault ride-through strategies. However, these methods cannot distinguish between faults at the end of a line and faults in the next-level line, and are only applicable to scenarios where there are no outgoing lines at the end of the line. For multi-level line scenarios, three-stage current protection is required to determine the fault location. Additionally, some existing technologies propose protection criteria for identifying faults within and outside the protection zone using kurtosis algorithms based on the boundary characteristics of current-limiting reactors. However, this method requires current-limiting reactors at both ends of the line. In DC distribution networks with many outgoing lines from converters, configuring current-limiting reactors on both sides of the line is not only costly, but also presents engineering challenges due to the direct connection of the reactors to the line. Summary of the Invention

[0005] In view of this, the present invention provides a DC distribution network fault detection method and related device based on high-frequency voltage on the line side of the magnetic ring boundary. It aims to extract high-frequency voltage components based on synchronous squeeze Stockwel transform, propose fault identification criteria inside and outside the zone under the action of magnetic ring boundary elements, reduce the cost of existing methods, and achieve effective identification of faults across the entire line range based on single-ended electrical quantities.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for detecting faults in a DC distribution network based on high-frequency voltage at the boundary line side of a magnetic ring, comprising the following steps:

[0008] Responding to the fault initiation criterion of the DC distribution network system under test; the fault initiation criterion is used to determine whether a disturbance has occurred in the DC distribution network system;

[0009] If the system experiences a disturbance, the polarity of the transient power after the fault is used to determine whether the fault direction is positive. If not, the system fault is determined to be negative. If it is, the subsequent steps are continued.

[0010] Calculate the mode 1 voltage fault component based on the positive and negative pole voltages on the magnetic ring circuit side;

[0011] Calculate the Stockwel transform of the mode 1 voltage fault component to obtain the time-frequency distribution matrix of the mode 1 voltage fault component;

[0012] A synchronous squeezing transformation is performed on the time-frequency distribution matrix to obtain the time-frequency distribution of the mode 1 voltage fault component after energy redistribution.

[0013] Based on the time-frequency distribution of the first-mode voltage fault component, the sum of the magnitudes of the first-mode voltage high-frequency fault components is calculated.

[0014] The system determines whether a fault is inside or outside the fault zone based on the sum of the magnitudes of the high-frequency fault components of the 1-mode voltage. If the sum of the magnitudes is not less than a set value, the system fault is determined to be an inside-zone fault. If the sum of the magnitudes is less than the set value, the system fault is determined to be a positive outside-zone fault.

[0015] Furthermore, the fault start criteria are as follows:

[0016]

[0017] In the formula, and These represent the calculated values ​​of the positive electrode voltage start-up criterion and the negative electrode voltage start-up criterion, respectively. This represents the setpoint value for the activation criterion;

[0018] The formulas for calculating the voltage start-up criteria for the positive and negative terminals are as follows:

[0019]

[0020] In the formula, and This indicates the positive and negative voltages on the circuit side of the magnetic ring. Indicates the sampling interval. Indicates the index of the current calculation time. This indicates the number of sampling points within the data window. This indicates the index of the sampling points within the data window.

[0021] Furthermore, the fault initiation criteria in response to the DC distribution network system under test include:

[0022] Collect the voltage on the magnetic ring circuit side and calculate the voltage start-up criterion value;

[0023] The fault initiation criterion is determined based on the calculated value of the voltage initiation criterion. If the criterion is met, the system is determined to have experienced a disturbance.

[0024] Furthermore, the mode 1 voltage fault component is calculated based on the positive and negative voltages on the magnetic ring circuit side, including:

[0025] The modulo-1 voltage is calculated using the voltages at the positive and negative terminals, as follows:

[0026]

[0027] In the formula, Indicates the modulus voltage. and This indicates the positive and negative voltages on the circuit side of the magnetic ring;

[0028] The fault component of the modulus voltage is calculated using the modulus voltage as follows:

[0029]

[0030] In the formula, Indicates the mode 1 voltage fault component. This indicates the modulus voltage within the data window prior to the fault. express The average value.

[0031] Furthermore, the time-frequency distribution matrix of the mode 1 voltage fault component is calculated according to the following formula:

[0032]

[0033] In the formula, This represents the time-frequency distribution matrix of the mode 1 voltage fault component. Indicates a point-in-time index. Indicates the sampling interval. This indicates the number of sampling points within the data window. Indicates the sampling point index. Indicates frequency index, This represents the modulo-1 voltage fault component, where i represents the imaginary unit.

[0034] Furthermore, the time-frequency distribution of the mode 1 voltage fault component after energy redistribution is determined according to the following formula:

[0035]

[0036] In the formula, This represents the time-frequency distribution of the mode 1 voltage fault component after energy redistribution. Represents a time variable. The frequency variable representing the synchronous extrusion S-transformation, Represents discrete frequency values. This represents the length of the k-th frequency interval. Represents the instantaneous frequency matrix. Indicates frequency interval, Indicates frequency Half of the frequency interval at that point, This represents the time-frequency distribution matrix of the mode 1 voltage fault component.

[0037] Furthermore, the sum of the moduli of the high-frequency fault components of the 1-mode voltage is determined according to the following formula:

[0038]

[0039] In the formula, This represents the sum of the magnitudes of the high-frequency fault components of the modulus voltage. The frequency variable representing the synchronous extrusion S-transformation, Indicates the effective operating frequency band range of the boundary. Represents a time variable. Indicates the length of the data window. This represents the time-frequency distribution of the mode 1 voltage fault component after energy redistribution.

[0040] Secondly, the present invention provides a DC distribution network fault detection device based on high-frequency voltage at the boundary line side of a magnetic ring, comprising:

[0041] The start-up judgment module is used to respond to the fault start-up criteria of the DC distribution network system under test; the fault start-up criteria are used to determine whether a disturbance has occurred in the DC distribution network system.

[0042] The first fault judgment module is used to determine whether the fault direction is positive when the system is disturbed by using the polarity of the transient power after the fault. If not, the system fault is determined to be negative. If so, the subsequent steps are continued.

[0043] The first calculation module is used to calculate the mode 1 voltage fault component based on the positive and negative pole voltages on the magnetic ring circuit side.

[0044] The second calculation module is used to calculate the Stockwel transform of the mode 1 voltage fault component and obtain the time-frequency distribution matrix of the mode 1 voltage fault component;

[0045] The third calculation module is used to perform synchronous squeezing transformation on the time-frequency distribution matrix to obtain the time-frequency distribution of the mode 1 voltage fault component after energy redistribution.

[0046] The fourth calculation module is used to calculate the sum of the magnitudes of the high-frequency fault components of the 1-mode voltage based on the time-frequency distribution of the 1-mode voltage fault components.

[0047] The second fault judgment module determines whether a fault is inside or outside the zone based on the sum of the magnitudes of the high-frequency fault components of the 1-mode voltage. If the sum of the magnitudes is not less than a set value, the system fault is determined to be an inside-zone fault. If the sum of the magnitudes is less than the set value, the system fault is determined to be a positive outside-zone fault.

[0048] Thirdly, the present invention provides a computer device, the device including a processor and a memory:

[0049] The memory is used to store computer programs and send the instructions of the computer programs to the processor;

[0050] The processor executes, according to the instructions of the computer program, a DC distribution network fault detection method based on the high-frequency voltage of the magnetic ring boundary line side, as described in the first aspect.

[0051] Fourthly, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements a DC distribution network fault detection method based on high-frequency voltage on the magnetic ring boundary line side as described in the first aspect.

[0052] In summary, this invention provides a method and related apparatus for detecting faults in a DC distribution network based on high-frequency voltage at the boundary line side of a magnetic ring. The method includes a fault initiation criterion responding to the DC distribution network system under test. The fault initiation criterion is used to determine whether a disturbance has occurred in the DC distribution network system. If a disturbance occurs, the polarity of the transient power after the fault is used to determine whether the fault direction is a positive fault. If not, the system fault is determined to be a reverse fault; if so, subsequent steps are continued. A modulo-1 voltage fault component is calculated based on the positive and negative voltages at the magnetic ring line side. The Stockwell transform of the modulo-1 voltage fault component is calculated to obtain the time-frequency distribution matrix of the modulo-1 voltage fault component. A synchronous squeezing transform is performed on the time-frequency distribution matrix to obtain the time-frequency distribution of the modulo-1 voltage fault component after energy redistribution. Based on the time-frequency distribution of the modulo-1 voltage fault component, the sum of the magnitudes of the high-frequency fault components of the modulo-1 voltage is calculated. The sum of the magnitudes of the high-frequency fault components of the modulo-1 voltage is used to determine whether the fault is inside or outside the fault zone. If the sum of the magnitudes is not less than a set value, the system fault is determined to be an inside-zone fault; if the sum of the magnitudes is less than the set value, the system fault is determined to be a positive outside-zone fault. This invention proposes a fault identification criterion for areas inside and outside the zone based on magnetic ring boundary elements and synchronous extrusion Stockwell transformation. It eliminates the need to configure high-cost and difficult-to-engineer current-limiting reactors on both sides, effectively reducing costs. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 A flowchart illustrating a DC distribution network fault detection method based on high-frequency voltage at the magnetic ring boundary line side, provided as an embodiment of the present invention;

[0055] Figure 2 A block diagram of a DC distribution network fault detection device based on high-frequency voltage at the boundary line side of a magnetic ring, provided in an embodiment of the present invention;

[0056] Figure 3 This is a block diagram of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0057] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0058] This invention provides a method for detecting faults in a DC distribution network based on high-frequency voltage at the boundary line side of a magnetic ring, comprising the following steps:

[0059] S1: Response to the fault initiation criterion of the DC distribution network system to be detected; the fault initiation criterion is used to determine whether a disturbance has occurred in the DC distribution network system.

[0060] It should be noted that the fault initiation criterion is a condition used to determine whether a disturbance has occurred in the DC distribution network system.

[0061] This step involves real-time monitoring of relevant electrical quantities in the DC distribution network. When these quantities meet pre-defined fault initiation criteria, it is assumed that a fault or disturbance may have occurred in the system, thus initiating the subsequent fault detection process. For example, a disturbance can be determined by voltage or current fluctuations exceeding a certain threshold.

[0062] S2: If a disturbance occurs in the system, the polarity of the transient power after the fault is used to determine whether the fault direction is a positive fault. If not, the system fault is determined to be a negative fault. If so, the subsequent steps are continued.

[0063] It should be noted that transient power refers to the change in power in the circuit during the transient process after a fault occurs. Power polarity refers to the direction of power flow; a positive direction fault usually means that the fault point is located on a specified positive direction side of the protection installation location, while a negative direction fault is the opposite.

[0064] After a fault occurs, transient power will be generated in the DC distribution network. Based on the power calculation formula and the measured voltage and current data, the polarity of the transient power is calculated. If the polarity of the transient power matches the characteristics of a positive-direction fault, the fault is considered a positive-direction fault, and subsequent detection steps continue; if it does not match, it is determined to be a reverse-direction fault, and appropriate measures can be taken or part of the detection process can be terminated as needed.

[0065] S3: Calculate the mode 1 voltage fault component based on the positive and negative voltages on the magnetic ring circuit side.

[0066] It should be noted that the 1-mode voltage fault component is a voltage component obtained by performing phase-mode transformation and other operations on the positive and negative pole voltages of the magnetic ring circuit side.

[0067] This step uses the phase-mode transformation formula to convert the positive and negative pole voltages measured on the magnetic ring circuit side into modulus form, from which the first-mode voltage fault component is extracted.

[0068] S4: Calculate the Stockwel transform of the mode 1 voltage fault component to obtain the time-frequency distribution matrix of the mode 1 voltage fault component.

[0069] It should be noted that the Stockwell transform (S-transform) is a time-frequency analysis method that combines the advantages of the short-time Fourier transform and the wavelet transform. It is suitable for analyzing non-stationary signals and can convert time-domain signals into time-frequency domain representations to obtain the time-frequency distribution matrix.

[0070] Based on the definition and formula of the Stockwell transform, the mode 1 voltage fault component obtained in step S3 is calculated. By selecting appropriate window functions and parameters, the mode 1 voltage fault component is expanded in both time and frequency dimensions to obtain its energy distribution at different times and frequencies, which is represented in the form of a time-frequency distribution matrix.

[0071] S5: Perform synchronous squeezing transformation on the time-frequency distribution matrix to obtain the time-frequency distribution of the 1-mode voltage fault component after energy redistribution.

[0072] It should be noted that synchronous squeezing transform is a method for optimizing time-frequency distribution. It can redistribute the energy in the time-frequency distribution, making the time-frequency representation more concentrated and improving the time-frequency resolution.

[0073] This step applies a synchronous squeezing transformation algorithm to the time-frequency distribution matrix obtained in step S4. This algorithm repositions and squeezes the frequency components in the time-frequency distribution, concentrating the energy of the same signal component, which was originally dispersed at different frequency points, near its true frequency. This results in a redistributed time-frequency distribution of the mode-1 voltage fault component, which more clearly shows the time-frequency characteristics of the fault signal.

[0074] S6: Based on the time-frequency distribution of the 1-mode voltage fault component, calculate the sum of the magnitudes of the 1-mode voltage high-frequency fault components.

[0075] It should be noted that the sum of moduli refers to the summation of the moduli of the high-frequency fault components of the modulus voltage within a certain frequency range. Here, the high-frequency fault components refer to the portion corresponding to the high-frequency band in the time-frequency distribution, and the range of the high-frequency band can be set according to the actual situation.

[0076] This step determines the range of the high-frequency band based on the time-frequency distribution of energy redistribution obtained in step S5, then extracts the magnitude values ​​of the mode 1 voltage fault components within this range, and adds these magnitude values ​​to obtain the sum of the magnitude values ​​of the mode 1 voltage high-frequency fault components. This sum of magnitude values ​​reflects the magnitude of the high-frequency fault energy.

[0077] S7: Based on the sum of the magnitudes of the high-frequency fault components of the 1-mode voltage, determine whether the fault is inside or outside the zone. If the sum of the magnitudes is not less than the set value, the system fault is determined to be an inside-zone fault. If the sum of the magnitudes is less than the set value, the system fault is determined to be a positive outside-zone fault.

[0078] It should be noted that the set value is a threshold value that is preset based on the specific parameters, operating conditions and protection requirements of the DC distribution network.

[0079] This step compares the sum of the magnitudes of the high-frequency fault components of the 1-mode voltage calculated in step S6 with a preset threshold. Since the magnetic ring boundary has different effects on the high-frequency signal depending on whether the fault is within or outside the zone, the high-frequency signal attenuation is smaller during an internal fault and significantly attenuated when passing through the boundary during an external fault. Therefore, if the sum of the magnitudes is not less than the preset value, it indicates a large high-frequency fault energy, and the fault is classified as internal; if the sum of the magnitudes is less than the preset value, it indicates a small high-frequency fault energy, and the fault is classified as a positive external fault.

[0080] This embodiment provides a fault detection method for DC distribution networks based on high-frequency voltage at the line side of a magnetic ring boundary. This method utilizes the characteristics of the magnetic ring boundary for high-frequency signals, employing steps such as fault initiation criteria and transient power polarity determination, combined with time-frequency analysis techniques such as Stockwell transform and synchronous squeezing transform, to extract effective fault features from the voltage at the line side of the magnetic ring. Compared to traditional methods, it eliminates the need for complex two-end measurement and communication, relying solely on voltage information from the single-end magnetic ring boundary to achieve fault direction determination and fault identification within and outside the fault zone. Furthermore, through time-frequency analysis and energy redistribution, it can more accurately capture high-frequency features during the transient fault process, improving the accuracy and reliability of fault detection. This method effectively solves the problem of rapid fault detection and location in DC distribution networks and has strong engineering application value.

[0081] Please see Figure 1 , Figure 1 This paper illustrates an implementation flow of a DC distribution network fault detection method based on high-frequency voltage at the magnetic ring boundary line side, designed according to the above embodiments. The implementation flow is further described below with reference to some other embodiments of the present invention. The implementation flow includes the following steps:

[0082] Step 1: Collect the voltage on the magnetic ring circuit side and calculate the fault initiation criterion.

[0083] In one embodiment of the present invention, the fault start criterion is as follows:

[0084] (1)

[0085] In the formula, and These represent the calculated values ​​for the positive and negative voltage start-up criteria, respectively. and It refers to the positive and negative voltages on the circuit side of the magnetic ring. N represents the sampling interval. s This indicates the number of sampling points within the data window. If the voltage start-up criteria for the positive and negative terminals satisfy the following formula, then the protection will start.

[0086] (2)

[0087] In the formula, This represents the setpoint for the activation criterion. If the criterion expressed in the above formula is satisfied, the system experiences a disturbance and proceeds to step 2.

[0088] Step 2: Determine the fault direction using the polarity of the transient power after the fault. If it is a positive fault, proceed to Step 3.

[0089] Step 3: Calculate the mode 1 voltage fault component.

[0090] In one embodiment of the present invention, firstly, the modulus voltage is calculated using the voltages of the positive and negative terminals, as shown in the following formula.

[0091] (3)

[0092] In the formula, This represents the mode-1 voltage. Based on the obtained mode-1 voltage, the mode-1 voltage fault component is calculated as shown in the following formula.

[0093] (4)

[0094] In the formula, This indicates the modulus voltage within the data window prior to the fault. express The average value.

[0095] Step 4: Calculate the Stockwel transform of the mode 1 voltage fault component.

[0096] In one embodiment of the present invention, the time-frequency distribution matrix determined by the Stockwell transform is as follows:

[0097] (5)

[0098] In the formula, This represents the time-frequency distribution matrix of the mode 1 voltage fault component. Indicates a point-in-time index. Indicates the sampling interval. This indicates the number of sampling points within the data window. Indicates the sampling point index. Indicates frequency index, This represents the modulo-1 voltage fault component, where i represents the imaginary unit.

[0099] Step 5: [Regarding...] Perform synchronous extrusion transformation.

[0100] In one embodiment of the present invention, firstly calculate The phase matrix is ​​obtained, and then the instantaneous frequency matrix is ​​obtained by differentiating the phase matrix. Energy redistribution is then performed based on the calculated instantaneous frequencies, as shown in the following equation.

[0101] (6)

[0102] In the formula, This represents the time-frequency distribution of the mode 1 voltage fault component after energy redistribution. Represents a time variable. The frequency variable representing the synchronous extrusion S-transformation, Represents discrete frequency values. This represents the length of the k-th frequency interval. Represents the instantaneous frequency matrix. Indicates frequency interval, Indicates frequency Half of the frequency interval at that location.

[0103] Step 6: Calculate the sum of the modulus values ​​of the high-frequency fault components of the 1-mode voltage.

[0104] In one embodiment of the present invention, the sum of the moduli is calculated as follows:

[0105] (7)

[0106] In the formula, Indicates the effective operating frequency band range of the boundary. Indicates the length of the data window. It represents the sum of the modulus values ​​of the high-frequency fault components of the 1-mode voltage.

[0107] Step 7: Determine whether the fault is inside or outside the zone, as shown in the following formula.

[0108] (8)

[0109] In the formula, This indicates the fault criterion setting value inside and outside the zone.

[0110] Based on the same inventive concept, this application also provides a DC distribution network fault detection device based on high-frequency voltage at the magnetic ring boundary line side for implementing the aforementioned DC distribution network fault detection method based on high-frequency voltage at the magnetic ring boundary line side. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations in the embodiments of the DC distribution network fault detection device based on high-frequency voltage at the magnetic ring boundary line side provided below can be found in the limitations of the DC distribution network fault detection method based on high-frequency voltage at the magnetic ring boundary line side described above, and will not be repeated here.

[0111] Please see Figure 2 This invention provides a DC distribution network fault detection device based on high-frequency voltage at the magnetic ring boundary line side, comprising:

[0112] The start-up judgment module is used to respond to the fault start-up criteria of the DC distribution network system under test; the fault start-up criteria are used to determine whether a disturbance has occurred in the DC distribution network system.

[0113] The first fault judgment module is used to determine whether the fault direction is positive when the system is disturbed by using the polarity of the transient power after the fault. If not, the system fault is determined to be negative. If so, the subsequent steps are continued.

[0114] The first calculation module is used to calculate the mode 1 voltage fault component based on the positive and negative pole voltages on the magnetic ring circuit side.

[0115] The second calculation module is used to calculate the Stockwel transform of the mode 1 voltage fault component and obtain the time-frequency distribution matrix of the mode 1 voltage fault component;

[0116] The third calculation module is used to perform synchronous squeezing transformation on the time-frequency distribution matrix to obtain the time-frequency distribution of the mode 1 voltage fault component after energy redistribution.

[0117] The fourth calculation module is used to calculate the sum of the magnitudes of the high-frequency fault components of the 1-mode voltage based on the time-frequency distribution of the 1-mode voltage fault components.

[0118] The second fault judgment module determines whether a fault is inside or outside the zone based on the sum of the magnitudes of the high-frequency fault components of the 1-mode voltage. If the sum of the magnitudes is not less than a set value, the system fault is determined to be an inside-zone fault. If the sum of the magnitudes is less than the set value, the system fault is determined to be a positive outside-zone fault.

[0119] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the system can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0120] Reference Figure 3 The present invention also provides a computer device, including: a memory and a processor, and a computer program stored in the memory. When the computer program is executed on the processor, it implements the DC distribution network fault detection method based on the high-frequency voltage of the magnetic ring boundary line side as described in any of the above methods.

[0121] The computer device may be a desktop computer, laptop, handheld computer, or cloud server, etc. This computer device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that... Figure 3 The examples of computer devices are merely examples and do not constitute a limitation on computer devices. They may include more or fewer components than shown in the illustration, or combinations of certain components, or different components. For example, they may also include input / output devices, network access devices, etc.

[0122] The processor referred to can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0123] In some embodiments, the memory may be an internal storage unit of the computer device, such as a hard drive or RAM. In other embodiments, the memory may be an external storage device of the computer device, such as a plug-in hard drive, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card. Furthermore, the memory may include both internal and external storage units of the computer device. The memory is used to store the operating system, applications, bootloader, data, and other programs, such as the program code of the computer program. The memory can also be used to temporarily store data that has been output or will be output.

[0124] This invention also provides a computer-readable storage medium storing a computer program thereon. When the computer program is run by a processor, it implements the DC distribution network fault detection method based on the high-frequency voltage of the magnetic ring boundary line side as described in any of the above methods.

[0125] In this embodiment, if the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a photographing device / terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electrical carrier signals or telecommunication signals.

[0126] This invention provides a computer program product, including a computer program that, when executed by a processor, implements the DC distribution network fault detection method based on the high-frequency voltage of the magnetic ring boundary line side as described in any of the above methods.

[0127] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0128] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0129] In the embodiments disclosed in this application, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling or direct coupling or communication connection may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0130] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A DC distribution network fault detection method based on high-frequency voltage at the boundary line side of a magnetic ring, characterized in that, Includes the following steps: Responding to a fault initiation criterion of the DC distribution network system to be tested; the fault initiation criterion is used to determine whether a disturbance has occurred in the DC distribution network system; If the system experiences a disturbance, the polarity of the transient power after the fault is used to determine whether the fault direction is positive. If not, the system fault is determined to be negative. If it is, the subsequent steps are continued. Calculate the mode 1 voltage fault component based on the positive and negative pole voltages on the magnetic ring circuit side; Calculate the Stockwell transform of the mode 1 voltage fault component to obtain the time-frequency distribution matrix of the mode 1 voltage fault component; The time-frequency distribution matrix is ​​subjected to synchronous squeezing transformation to obtain the time-frequency distribution of the mode 1 voltage fault component after energy redistribution; Based on the time-frequency distribution of the 1-mode voltage fault component, calculate the sum of the magnitudes of the 1-mode voltage high-frequency fault components; The system determines whether a fault is inside or outside the zone based on the sum of the magnitudes of the high-frequency fault components of the 1-mode voltage. If the sum of the magnitudes is not less than a set value, the system fault is determined to be an inside-zone fault. If the sum of the magnitudes is less than the set value, the system fault is determined to be a positive outside-zone fault. The time-frequency distribution of the mode 1 voltage fault component after energy redistribution is determined by the following formula: ； In the formula, This represents the time-frequency distribution of the mode 1 voltage fault component after energy redistribution. Represents a time variable. The frequency variable representing the synchronous extrusion S-transformation, Represents discrete frequency values. This represents the length of the k-th frequency interval. Represents the instantaneous frequency matrix. Indicates frequency interval, Indicates frequency Half of the frequency interval at that point, This represents the time-frequency distribution matrix of the mode 1 voltage fault component.

2. The DC distribution network fault detection method based on high-frequency voltage at the magnetic ring boundary line side according to claim 1, characterized in that, The fault initiation criteria are as follows: ； In the formula, and These represent the calculated values ​​of the positive electrode voltage start-up criterion and the negative electrode voltage start-up criterion, respectively. This represents the setpoint value for the activation criterion; The formulas for calculating the voltage start-up criteria for the positive and negative terminals are as follows: ； In the formula, and This indicates the positive and negative voltages on the circuit side of the magnetic ring. Indicates the sampling interval. Indicates the index of the current calculation time. This indicates the number of sampling points within the data window. This indicates the index of the sampling points within the data window.

3. The DC distribution network fault detection method based on high-frequency voltage at the magnetic ring boundary line side according to claim 2, characterized in that, The fault initiation criteria in response to the DC distribution network system under test include: Collect the voltage on the magnetic ring circuit side and calculate the voltage start-up criterion value; Based on the calculated value of the voltage start criterion, determine whether the fault start criterion is met. If so, determine that the system has experienced a disturbance.

4. The DC distribution network fault detection method based on high-frequency voltage at the magnetic ring boundary line side according to claim 1, characterized in that, The modulus voltage fault component is calculated based on the positive and negative pole voltages on the magnetic ring circuit side, including: The modulo-1 voltage is calculated using the voltages at the positive and negative terminals, as follows: ； In the formula, Indicates the modulus voltage. and This indicates the positive and negative voltages on the circuit side of the magnetic ring; The fault component of the mode 1 voltage is calculated using the aforementioned mode 1 voltage, as follows: ； In the formula, Indicates the mode 1 voltage fault component. This indicates the modulus voltage within the data window prior to the fault. express The average value.

5. The DC distribution network fault detection method based on high-frequency voltage at the magnetic ring boundary line side according to claim 1, characterized in that, The time-frequency distribution matrix of the mode 1 voltage fault component is calculated according to the following formula: ； In the formula, This represents the time-frequency distribution matrix of the mode 1 voltage fault component. Indicates a point-in-time index. Indicates the sampling interval. This indicates the number of sampling points within the data window. Indicates the sampling point index. Indicates frequency index, This represents the modulo-1 voltage fault component, where i represents the imaginary unit.

6. The DC distribution network fault detection method based on high-frequency voltage at the magnetic ring boundary line side according to claim 1, characterized in that, The sum of the modulus values ​​of the high-frequency fault components of the modulus voltage is determined by the following formula: ； In the formula, This represents the sum of the magnitudes of the high-frequency fault components of the modulus voltage. The frequency variable representing the synchronous extrusion S-transformation, Indicates the effective operating frequency band range of the boundary. Represents a time variable. Indicates the length of the data window. This represents the time-frequency distribution of the mode 1 voltage fault component after energy redistribution.

7. A DC distribution network fault detection device based on high-frequency voltage at the boundary line side of a magnetic ring, characterized in that, include: The start-up judgment module is used to respond to the fault start-up criteria of the DC distribution network system under test; The fault initiation criterion is used to determine whether a disturbance has occurred in the DC distribution network system; The first fault judgment module is used to determine whether the fault direction is positive when the system is disturbed by using the polarity of the transient power after the fault. If not, the system fault is determined to be negative. If so, the subsequent steps are continued. The first calculation module is used to calculate the mode 1 voltage fault component based on the positive and negative pole voltages on the magnetic ring circuit side. The second calculation module is used to calculate the Stockwell transform of the mode 1 voltage fault component to obtain the time-frequency distribution matrix of the mode 1 voltage fault component. The third calculation module is used to perform synchronous squeezing transformation on the time-frequency distribution matrix to obtain the time-frequency distribution of the mode 1 voltage fault component after energy redistribution. The fourth calculation module is used to calculate the sum of the magnitudes of the high-frequency fault components of the 1-mode voltage based on the time-frequency distribution of the 1-mode voltage fault components; The second fault judgment module determines whether a fault is inside or outside the zone based on the sum of the magnitudes of the high-frequency fault components of the 1-mode voltage. If the sum of the magnitudes is not less than a set value, the system fault is determined to be an inside-zone fault. If the sum of the magnitudes is less than the set value, the system fault is determined to be a positive outside-zone fault. The time-frequency distribution of the mode 1 voltage fault component after energy redistribution is determined by the following formula: ； In the formula, This represents the time-frequency distribution of the mode 1 voltage fault component after energy redistribution. Represents a time variable. The frequency variable representing the synchronous extrusion S-transformation, Represents discrete frequency values. This represents the length of the k-th frequency interval. Represents the instantaneous frequency matrix. Indicates frequency interval, Indicates frequency Half of the frequency interval at that point, This represents the time-frequency distribution matrix of the mode 1 voltage fault component.

8. A computer device, characterized in that, The device includes a processor and a memory: The memory is used to store computer programs and send the instructions of the computer programs to the processor; The processor executes, according to the instructions of the computer program, a DC distribution network fault detection method based on high-frequency voltage on the magnetic ring boundary line side as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements a DC distribution network fault detection method based on high-frequency voltage on the magnetic ring boundary line side as described in any one of claims 1-6.

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